Balance weight for a rotary component in turbomachinery, methods of installation and installation tools

ABSTRACT

A balance weight has first and second margins at right angles to one another with the second margin larger than the first margin. A balance weight groove in a rotor has outer and inner wall portions, with the outer wall portions spaced a distance less than the spacing between the inner wall portions. The balance weight has a central threaded opening receiving a screw and a driving slot in the upper face of the weight. An insertion tool is threaded to the balance weight to insert the balance weight through a turbomachinery access opening into the groove. The tool is rotated to locate the second margins below the outer wall portions of the groove. By inserting a driving tool through the insertion tool, the screw is rotated to lock the balance weight to the rotor and in the groove. Upon removal of the insertion and driving tools, a staking tool is inserted through turbine access opening to stake the balance weight and rotor and the screw and balance weight.

BACKGROUND OF THE INVENTION

The present invention relates to a balance weight receivable in abalance weight groove in turbomachinery, for example, a steam turbine,methods of remotely installing the balance weight in the groove withoutremoval of turbomachinery casing and tools for installing the balanceweight within the groove.

In the manufacture of turbomachinery, for example, steam turbines, finalbalancing of the rotating component is an essential and important step.Also, at several times during the life of a steam turbine, it is usuallynecessary to rebalance the rotating component. This is typicallyaccomplished by adding weights to the rotors to compensate for therotational effects of a bowed rotor, missing or modified rotorcomponents such as buckets or covers, or to lower the vibration levelsat which the unit is operating. Weight grooves used to balance rotorsduring manufacture of a turbine conventionally have a T-shaped ordovetail configuration. Access ports through the casing are typicallynot provided in older turbines. The weights manufactured as originalequipment in such turbines are usually dovetail or T-shaped inconfiguration and require staking to fix the weights to the rotarycomponent. For balance weight grooves that are intended for rebalancingduring service, access ports are typically provided through the casingsand the balance weights are usually of a screw plug type.

To convert a rotor that had only a factory balance weight provision toone capable of field balancing, it is necessary to increase the volumeof material available for the installation of screw-type plug weights bywelding. This process was very time-consuming and expensive.Additionally, the welding process, because of the input of heat to therotor forging, required that the material be stress-relieved afterwelding. Re-machining of many of the tight fits on the rotor body wasalso frequently necessary after the welding and stress relief. Thisprocess was also expensive as the rotor required removal from theturbine before the necessary machining tools could be utilized to effectthe changes. Also, the casing needed to be modified to provide an accessport through which field balance weights could be installed in therotor. Consequently, there is a need to provide a balance weight/groovecombination for both factory and field installation, a method ofinstalling the balance weight in the groove and tools for effecting theinstallation.

BRIEF SUMMARY OF THE INVENTION

In accordance with a preferred embodiment of the present invention,there is provided a balance weight for insertion in a groove of arotating component, for example, a rotor of turbomachinery. Preferably,the groove has a wedge or dovetail configuration or a T-shaped slot.Particularly, the balance weight has a configuration generallycomplementary to the cross-sectional configuration of the groove.Characteristically, outer and inner wall portions of each type of grooveare spaced respective first and second distances from one another, withthe second distance being greater than the first distance. The balanceweight has first margins having a first dimension less than the firstdistance, enabling the balance weight in a first orientation to beinserted into the groove. The balance weight also has second marginshaving a second dimension greater than the first distance such that,upon rotation of the balance weight in the groove into a secondorientation, the second margins lie within the groove inwardly of theouter wall portions of the groove. Additionally, a screw is threadedthrough the balance weight. By threading the screw with the balanceweight in the groove, the balance weight is elevated within the grooveto engage the second margins of the balance weight against the opposingouter walls of the groove to retain the balance weight within thegroove. With the balance weight thus engaged, the balance weight can bestaked to the rotor and the screw staked to the balance weight.

To install the balance weight, an installation tool is inserted throughaccess openings in the casing and releasably carries the balance weightat a distal end of the tool for insertion into the groove. The insertiontool comprises an elongated body, preferably tubular, having at leastone and preferably two rods, generally coextensive with the body andwhich rods are rotatable for screwthreaded engagement with femalethreaded sockets on the balance weight such that the balance weight canbe disposed within the turbomachinery through an access opening in itscasing by the installation tool and inserted in the groove. Theinsertion tool also includes a head shaped for reception in acomplementary-shaped slot on the balance weight whereby, by rotating theinsertion tool, the balance weight can be rotated within the groove fromits first orientation to its second orientation to locate the secondmargins below the outer wall portions. The insertion tool also includesa central opening through its body through which is received anelongated driver. The driver has a head for engaging the screw of thebalance weight. By rotating the driver and hence the screw, the balanceweight is elevated within the groove such that the second margins engagethe outer wall portions of the groove to clamp the balance weight to therotor against circumferential, rotational and radial movement. Theinsertion tool is then detached from the balance weight by unthreadingthe rod(s) from the balance weight and withdrawn through the accessopening. Subsequently, a staking tool is inserted through the accessopenings. The staking tool has a pair of staking projections for stakingthe balance weight and the rotor component to one another. The stakingtool also includes another staking projection to stake the balanceweight and screw to one another.

In a preferred embodiment according to the present invention, there isprovided apparatus for balancing a rotational component about an axis ofrotation, comprising a rotor having a generally circumferentiallyextending groove at least in part about the axis of rotation, opposingwalls of the groove having inner and outer portions with the outer wallportions spaced a first distance from one another and the inner wallportions spaced a second distance from one another greater than thefirst distance, a balance weight having first margins with a firstdimension less than the first distance enabling the balance weight, in afirst orientation relative to the groove, for reception in the groove,the balance weight having second margins with a second dimension greaterthan the first dimension and the first distance such that, upon rotationof the balance weight in the groove to a second orientation relative tothe groove, the second margins lie within the groove inwardly of and inregistration with the outer wall portions and a screw threadedlyreceived in the balance weight and engageable with a base of the groove,the balance weight being displaceable away from the base in response torotation of the screw relative to the balance weight to engage thesecond margins against the outer wall portions to retain the balanceweight in the groove against circumferential and outward movementthereof relative to the groove.

In a further preferred embodiment according to the present invention,there is provided for use in balancing a rotor about an axis of rotationwherein the rotor has a generally circumferentially extending grooveextending at least in part about the axis of rotation, a balance weight,comprising a balance weight body having first margins opposite oneanother and spaced from one another a first dimension enabling thebalance weight body for reception in the groove, the balance weight bodyhaving second margins opposite one another and spaced from one another asecond dimension greater than the first dimension for disposition withinthe groove, the fist and second margins of the balance weight body beinggenerally oriented 90° relative to one another about the body and ascrew threadedly received in the balance weight for engaging a base ofthe groove, the balance weight body having an outer face with a slot forreceiving a tool to rotate the balance weight.

In a still further preferred embodiment according to the presentinvention, there is provided a method of remotely installing a balanceweight in a groove of a rotary component in turbomachinery having atleast one casing surrounding the rotary component, comprising the stepsof attaching a balance weight to the end of an elongated insertion tool,inserting the balance weight and tool through an access opening in thecasing, locating the balance weight in the balance weight groove usingthe insertion tool, rotating the balance weight in the groove toregister marginal portions of the balance weight below marginal wallportions of the groove, securing the balance weight in the groove bythreading a screw through the balance weight to engage the base of thegroove and engage the marginal portions of the balance weight againstthe marginal wall portions of the groove, detaching the tool from thebalance weight and withdrawing the tool through the access opening.

In a still further preferred embodiment according to the presentinvention, there is provided an insertion tool for remotely inserting abalance weight through an access opening in a casing of turbomachineryinto a groove of a rotary component thereof and rotating the balanceweight within the groove, comprising an elongated tool body having ahandle at a proximal end, a central opening through the tool body, and atool head at an opposite distal end for engaging and rotating thebalance weight, a pair of rods carried by the body straddling thecentral opening and rotatable relative to the tool body for releasablesecurement at distal ends to the balance weight, the handle enablingrotation of the tool body and the rods to rotate the balance weight inthe groove.

In a still further preferred embodiment according to the presentinvention, there is provided a kit for remotely inserting a balanceweight through an access opening in a casing of turbomachinery into agroove of a rotary component thereof and securing the balance weightwithin the groove, comprising an elongated tool body having a handle ata proximal end, a central opening through the body, and a tool head atan opposite distal end for engaging and rotating the balance weight, apair of rods carried by the body straddling the tool body and rotatablerelative to the tool body for releasable securement at distal ends tothe balance weight, a driver receivable within the central opening forrotating a screw to engage the balance weight against marginal walls ofthe groove to secure the balance weight within the groove and a stakingtool comprising an elongated staking tool body terminating at a distalend in a staking projection for staking the balance weight and rotarycomponent to one another.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary cross-sectional view illustrating a balanceweight groove in a rotor of a turbomachine and a balance weight forinsertion into the groove;

FIG. 2 is a view similar to FIG. 1 with the balance weight inserted intothe groove;

FIG. 3 is a view similar to FIGS. 1 and 2 illustrating the balanceweight clamped within the groove;

FIG. 4 is a view illustrating the balance weight finally secured andstaked within the groove;

FIG. 5 is a perspective view of an insertion tool, together with adriver, and illustrated with parts broken out and in cross-section,poised for engagement with the balance weight; and

FIG. 6 is an enlarged perspective view with parts broken out and incross-section illustrating a staking tool for finally staking thebalance weight and rotor to one another and the balance weight and screwto one another.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, particularly to FIG. 1, there isillustrated a rotational component including, for example, a rotor Rrotatable about an axis of rotation extending in the direction of arrow10. The rotor R includes a circumferentially extending groove 12, thecircumferential direction being indicated by the arrow 14. Asillustrated, the groove 12 may extend in part or wholly about the rotorR and includes opposing walls 16 and 18 and a base 20. The groove 12includes outer and inner wall portions 22 and 24, respectively, theouter wall portions 22 being spaced a first distance D1 less than thedistance D2 between the inner wall portions 24. In the illustratedpreferred embodiment, the groove 12 comprises an inverted, generallyT-shaped groove wherein the outer wall portions 22 comprise axiallyopposed flanges. It will be appreciated that the groove may have othershapes such as a wedge or dovetail shape, it being sufficient that inall such configurations the inner wall portions, e.g., portions 24, areseparated from one another a distance greater than the outer wallportions, e.g., portions 22, are separated from one another.

A balance weight 30 is also illustrated in FIG. 1 poised for insertioninto the groove 12 as indicated by bracket 29 and forming part of therotational component when inserted. Balance weight 30 includes a balanceweight body 32 having lower and upper sections 34 and 36, respectively.Upper section 36 has a generally circular configuration, while the lowersection 34 has first and second pairs of margins 38 and 40,respectively. First margins 38 lie on opposite sides of the balanceweight 30 and have a first dimension or separation distance d1therebetween corresponding generally to the diameter of the uppersection 36. The width of the balance weight defined by the firstdimension is also less than the distance D1 between the outer portions22 of the axially opposed walls of groove 12. Balance weight 30 alsoincludes a second pair of opposite margins 40 which project outwardlyfrom opposite ends of the balance weight and beyond the periphery of theupper section 36. Thus, the second margins 40 define the length of thebalance weight and are spaced from one another a second dimension d2,i.e.,a second diameter, greater than the first distance D1 and slightlyless than the distance D2. The second margins constitute flanges whichproject in opposite directions, comers of the flanges in the directionof rotation of the balance weight as described below being rounded orarcuate at 42.

The balance weight 30 also includes a central female threaded opening 44extending between outer and inner faces of the balance weight. A malethreaded screw 46 is threadedly received in the female threaded balanceweight opening 44 and includes a socket 48 for receiving a tool, asdescribed below. Altematively, the socket may be replaced by a slot orPhillips head or other type of connector for receiving the head of adriving tool. Balance weight 30 also includes an outer face 50 having adiametrical slot 52 extending between opposite sides of the weight 30and oriented such that the opposite ends of the slot lie generally flushwith the second margins 38 of the lower section. A pair of femalethreaded apertures 54 open through the outer face 50 into the slot 52and lie on opposite sides of the female threaded central opening 44. Theoutwardly projecting bosses 56 on opposite sides of the slot 52 havegrooves 58 extending generally perpendicular to the slot 52 for reasonsdescribed hereinafter.

Referring to FIGS. 1-4, the sequence of movement of the balance weightrelative to the groove 12 to finally secure the balance weight in thegroove is illustrated. Initially, the balance weight 30 is initiallyoriented such that the margins 38 lie generally parallel to the outerwall portions 22 of the groove 12, i.e., the long dimension of thebalance weight is aligned in the circumferential direction of thegroove. In this first orientation the balance weight 30 can be insertedinto the groove past the outer wall portions 22 such that the lowersection 34 lies wholly within the groove between the inner wall portions16. In this first orientation, it will be appreciated that the uppersection 36 lies between the outer wall portions 22 and the lower face ofthe balance weight bears against the base 20 of groove 12. ComparingFIGS. 2 and 3, it will be seen that the balance weight is rotated in thegroove approximately 90° into a second orientation illustrated in FIG. 3.By rotating the balance weight with the arcuate surfaces 42 of theflanges leading in the direction of rotation, the second margins 40 ofthe balance weight are located below or inwardly of the outer wallportions 22. With the balance weight oriented as illustrated in FIG. 3,the screw 46 is then rotated to bear against the base 20 of groove 12and displace the balance weight away from the base to engage the outersurfaces of the second margins 40 against the outer wall portions, i.e.,the undersides of the outer wall portions 22 to lock the balance weightin the groove against circumferential and outward movement relative tothe groove. Consequently, the inner face of the balance weight is spacedfrom the base of the groove and the outer face of the outer section liesgenerally flush with the surface of the rotor. To finally secure thebalance weight in the groove, the balance weight and rotor are staked toone another and the set screw is staked to the balance weight.

In order to install the balance weight in the groove, particularly in aturbine in service, an access opening through the casing of theturbomachinery is formed if an access opening is not already available.Also, a kit comprised of a number of different tools is provided.Referring to FIG. 5, the kit comprises an insertion tool, generallydesignated 70, a driver tool, generally designated 72, and a stakingtool, generally designated 74 (FIG. 6). The insertion tool 70 comprisesan elongated tube 76 having a handle 78 at a proximal end of the tube.The tube 76 has a central opening 80 throughout its length and opensthrough the proximal end of the tube 76 and handle 78 at 82 and througha tool head 84 at the distal end of the tool 70. The tool head 84comprises a projection for reception in the slot 52 of the balanceweight.

The tool 70 also includes a rod, and preferably two rods 86, whichextend through openings in handle 78 and through a guide ring 88adjacent the distal end of the tube 76. The rods 86 thus straddle tube76. The rods 86 also have male threads 90 at their distal ends forthreaded engagement in the female threaded apertures 54 of the balanceweight. The rods 86 are rotatably received through the apertures in thehandle 78 and guide ring 88 to enable the rods to be threaded to andunthreaded from the balance weight.

The drive tool 72 includes an elongated rod 92 terminating at its distalend in a tool head 94 complementary to the socket of screw 46 or othertype of driven connection of the screw 46. The tool 72 also includes ahandle 96 at its proximal end such that the tool can be rotated. The rod92 is sized for reception within the central opening 80 through tube 76.

Referring to FIG. 6, the staking tool 74 includes an elongated rod 100terminating at its lower end in staking projections. Particularly, apair of staking projections 102 are disposed at the lower end of tool 74a distance slightly greater than the distance D1 such that theprojections 102 may engage the outer surfaces of the rotor on oppositesides of the groove 58 and adjacent the slots 58, respectively. Acentral projection 104 on the distal end of tool 74 has a pair ofprojections 106 spaced from one another a distance corresponding to thediameter of the screw.

To use the tools to install the balance weight, the rods 86 are insertedthrough the handle 78 and guide ring 88 and threaded into the apertures54 to attach the tool 70 to the balance weight. It will be appreciatedthat the tool head 84 is thereby received within the slot 82. The toolwith attached balance weight is then inserted through one or more accessopenings 85 in the casing 87 of the turbine (see FIG. 5). The tool 70 ismanipulated to orient and align the width of the balance weight with thecircumferential extent of the groove such that the balance weight can beinserted into the groove past the outer wall portions 22 as illustratedin FIG. 2. With the second margins 40 below but not in registration withthe outer wall portions 22, the tool 70 is rotated to rotate the balanceweight in the groove to register the second margins 40 below the outerwall portions 22. To lock the balance weight within the groove, the tool72 is then inserted through the central opening 80 such that its toolhead 94 engages the socket of the screw 46. By rotating the tool 72relative to the tool 70 and threading the screw 46 relative to thebalance weight, the balance weight is displaced away from the base ofthe groove to engage the second margins 40 against the underside of theouter wall portions 22 as illustrated in FIG. 3. With the balance weightthus locked in place, the rods 86 may be unthreaded from the balanceweight by rotating the rods from locations above the handle 78 todisconnect tool 70 from the balance weight. The tool 70 is thenwithdrawn from the access openings of the turbomachinery casing.

To stake the balance weight and rotor to one another and the screw andthe balance weight to one another, the staking tool 70 is then insertedthrough the access openings to engage the balance weight. Particularly,the projections 102 engage the margin of the rotor adjacent slot 58 andcentral projection 104 engages the margin of the balance weightsurrounding the screw. By impacting the staking tool 74, for example,with a hammer, the metal of the rotor is upset to secure the balanceweight and the rotor to one another with the deformed metal in partentering slots 58. Likewise, the metal of the balance weight is upset bythe projections 106 to secure the balance weight and screw to oneanother with the deformed metal of the balance weight in part engagingthe screw.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A component rotatable about an axis of rotation,comprising: a rotor having a substantially circumferentially extendinggroove at least in part about the axis of rotation, opposing walls ofsaid groove having inner and outer portions with said outer wallportions spaced a first distance from one another and said inner wallportions spaced a second distance from one another greater than saidfirst distance; a balance weight having a rotational axis and firstmargins, said first margins having a first diameter about saidrotational axis less than said first distance enabling said balanceweight, in a first orientation about said rotational axis and relativeto said groove, for reception in said groove; said balance weight havingsecond margins having a second diameter about said rotational axisgreater than said first diameter and said first distance, the first andsecond margins having the respective first and second diameters beingoriented about said rotational axis approximately 90° relative to oneanother such that, upon rotation of said balance weight approximately90° in said groove from said first orientation to a second orientation,the second margins lie within said groove inwardly of and inregistration with said outer wall portions; and a screw threadedlyreceived in said balance weight and engaging a base of said groove, saidbalance weight being displaceable away from said base in response torotation of said screw relative to said balance weight to engage saidsecond margins against said outer wall portions to retain the balanceweight in the groove against circumferential and outward movementthereof relative to said groove.
 2. A component to claim 1 wherein saidbalance weight has an outer face with a slot for receiving a tool torotate the balance weight relative to said grove.
 3. A componentaccording to claim 1 wherein said outer wall portions comprise flangesprojecting toward one another, said second margins of said balanceweight in said second orientation thereof being located below saidflanges in said groove and engaging with said flanges in response torotation of said screw relative to said balance weight.
 4. A componentrotatable about an axis of rotation, comprising: a rotor having asubstantially circumferentially extending groove at least in part aboutthe axis of rotation, opposing walls of said groove having inner andouter portions with said outer wall portions spaced a first distancefrom one another and said inner wall portions spaced a second distancefrom one another greater than said first distance; a balance weighthaving first margins with a first dimension less than said firstdistance enabling said balance weight, in a first orientation relativeto said groove, for reception in said groove; said balance weight havingsecond margins with a second dimension greater than said first dimensionand said first distance such that, upon rotation of said balance weightin said groove to a second orientation relative to said groove, thesecond margins lie within said groove inwardly of and in registrationwith said outer wall portions; a screw threadedly received in saidbalance weight and engaging a base of said groove, said balance weightbeing displaced away from said base in response to rotation of saidscrew relative to said balance weight to engage said second marginsagainst said outer wall portions to retain the balance weight in thegroove against circumferential and outward movement thereof relative tosaid groove; said outer wall portions comprising flanges projectingtoward one another, said second margins of said balance weight in saidsecond orientation thereof being located below said flanges in saidgroove and engaged with said flanges in response to rotation of saidscrew relative to said balance weight; and said second marginscomprising second flanges projecting from said balance weight, saidsecond flanges having arcuate edges along one side thereof facing in thedirection of rotation of the balance weight within the groove.
 5. Acomponent rotatable about an axis of rotation, comprising: a rotorhaving a substantially circumferentially extending groove at least inpart about the axis of rotation, opposing walls of said groove havinginner and outer portions with said outer wall portions spaced a firstdistance from one another and said inner wall portions spaced a seconddistance from one another greater than said first distance; a balanceweight having first margins with a first dimension less than said firstdistance enabling said balance weight, in a first orientation relativeto said groove, for reception in said groove; said balance weight havingsecond margins with a second dimension greater than said first dimensionand said first distance such that, upon rotation of said balance weightin said groove to a second orientation relative to said groove, thesecond margins lie within said groove inwardly of and in registrationwith said outer wall portions; a screw threadedly received in saidbalance weight and engaging a base of said groove, said balance weightbeing displaced away from said base in response to rotation of saidscrew relative to said balance weight to engage said second marginsagainst said outer wall portions to retain the balance weight in thegroove against circumferential and outward movement thereof relative tosaid groove; and said balance weight having an outer face including apair of female threaded openings for receiving male threaded rods forremotely installing the balance weight in the groove.
 6. A componentrotatable about an axis of rotation, comprising: a rotor having asubstantially circumferentially extending groove at least in Part aboutthe axis of rotation, opposing walls of said groove having inner andouter portions with said outer wall portions spaced a first distancefrom one another and said inner wall portions spaced a second distancefrom one another greater than said first distance; a balance weighthaving first margins with a first dimension less than said firstdistance enabling said balance weight, in a first orientation relativeto said groove, for reception in said groove; said balance weight havingsecond margins with a second dimension greater than said first dimensionand said first distance such that, upon rotation of said balance weightin said groove to a second orientation relative to said groove, thesecond margins lie within said groove inwardly of and in registrationwith said outer wall portions; a screw threadedly received in saidbalance weight and engaging a base of said groove, said balance weightbeing displaced away from said base in response to rotation of saidscrew relative to said balance weight to engage said second marginsagainst said outer wall portions to retain the balance weight in thegroove against circumferential and outward movement thereof relative tosaid groove; and said balance weight having an outer face with a slotfor receiving a tool to rotate the balance weight relative to saidgroove from said first orientation to said second orientation, saidouter wall portions comprising flanges projecting toward one another,said second margins of said balance weight in said second orientationthereof being located in said groove below said flanges and engagingsaid flanges in response to rotation of said screw relative to saidbalance weight, said second margins comprising second flanges projectingfrom said balance weight, said second flanges having arcuate edges alongone side thereof facing in the direction of rotation of the balanceweight within the groove, said outer face including a pair of femalethreaded openings for receiving male threaded rods for remotelyinstalling the balance weight in the groove.
 7. A component rotatableabout an axis of rotation, comprising: a rotor having a substantiallycircumferentially extending groove at least inp art about the axis ofrotation, opposing walls of said groove having inner and outer portionswith said outer wall portions spaced a first distance from one anotherand said inner wall portions spaced a second distance from one anothergreater than said first distance; a balance weight having first marginswith a first dimension less than said first distance enabling saidbalance weight, in a first orientation relative to said groove, forreception in said groove; said balance weight having second margins witha second dimension greater than said first dimension and said firstdistance such that, upon rotation of said balance weight in said grooveto a second orientation relative to said groove, the second margins liewithin said groove inwardly of and in registration with said outer wallportions; a screw threadedly received in said balance weight andencaging a base of said groove, said balance weight being displaced awayfrom said base in response to rotation of said screw relative to saidbalance weight to engage said second margins against said outer wallportions to retain the balance weight in the groove againstcircumferential and outward movement thereof relative to said groove:and said groove having a substantially T-shaped configuration.